Unit for draining water from a fuel filter

ABSTRACT

An automatic bleed unit for a fuel filter used particularly in diesel engines includes a filter chamber  5  for accumulating water present in the fuel. Sensors  220, 230  and associated floats  24, 25  are provided for determining the level of water in the chamber. Upon reaching a predetermined level, a microprocessor activates a withdrawal device  7  to drain water from the chamber. The device is only activated when the vehicle engine is at rest and the ignition key is in first switch position that makes the relevant electrical system live. A system that verifies the compatibility between the withdrawal device casing  70  and a base part  20  of the sensing system can also be included.

TECHNICAL FIELD

This invention relates to improvements in the automatic bleed unit for adisposable filter fully described in PCT/IB00/01527 Published asWO01/33069 A1 in the name of the same Applicant, the text of which is tobe considered an integral part of the present description for suitablereference.

BACKGROUND ART

Essentially, the device of said document comprises a sensor meansassociated with the chamber of the filter for the vehicle fuel (such asdiesel oil) in which the water present in said fuel accumulates, awithdrawal device provided for discharging said water when it reaches apredetermined maximum level, and a microprocessor (or electronic card)which is connected to said sensor means and to said withdrawal devicesuch as to activate this latter, with the vehicle engine at rest and therelative electrical system live, when the water reaches saidpredetermined maximum level.

In particular with said vehicle electrical system there is associated avisual indicator which is activated by the sensor means via themicroprocessor, the said microprocessor being arranged to maintain thewithdrawal device deactivated when the vehicle engine rotates and saidvisual indicator is energized. Said sensor means also comprises twomutually movable elements, of which one is permanently associated withthe shell of the filter in which the water collects, and which isdisposable, whereas the other is positioned inside a casing whichcontains said microprocessor and said withdrawal device, is removablyconnected to said shell, and is permanently associated with the vehicle.

For further details reference should be made to the text of theapplication cited in the introduction.

A problem which has been encountered in using the aforedescribed unitderives from the fact that the sensor means may sometimes not intervenedue to its two component elements being unable to move relative to oneanother, and the difficulties resulting therefrom. Investigations haveshown that said lack of intervention is mainly due to at least one ofthe following reasons.

Materials such as impurities, dirt or adhesive lumps can deposit on theelement permanently associated with the vehicle, to hinder sliding ofthe element associated with the filter, even when this is new and clean.

In addition, as one of the two elements is replaced when the filter isreplaced, dimensional inaccuracies can occur between these elements,particularly if the used and new filters pertain to different batches ororiginate from different operating lines. In this case couplinginaccuracies and/or misalignments thereof can occur when the shell ofthe new filter is connected to said water withdrawal device.

The main object of the present invention is to obviate the aforesaidproblem within the context of a simple, rational, reliable andeconomical construction.

DISCLOSURE OF THE INVENTION

Said object is attained by virtue of the characteristics indicated inthe claims.

In attaining said object, according to the invention said sensor meansof the known unit cited in the introduction is made to consist of adifferential water level reading and monitoring system comprising twomeasurement members, each sensitive to a level between the maximumpredetermined level and the depth of said accumulation chamber, said twomeasurement members being connected to the unit microprocessor suchthat, with the vehicle engine at rest and the relative electrical systemlive, it energizes said withdrawal device in response to the signalreceived from one or other of said two members.

Moreover, apart from the respective external electric cabling, and aswill be apparent hereinafter, the constituent elements of said twomeasurement members are advantageously permanently positioned in thelower part of the accumulation chamber of the disposable filter.

Finally, means described hereinafter are interposed between saiddifferential reading and monitoring system and that part of the bleedunit permanently associated with the visual indicator, to verify thecompatibility between the filter and the bleed unit. By virtue of theaforegoing, all the objects of the invention are attained.

In this respect, the danger of non-intervention of the sensor means isreduced to a minimum in that on the one hand the activation signal forthe bleeding stage is generated even if the reading member is disabledby the presence of excessive deposits of foreign material, and on theother hand a filter having characteristics different from those requiredby the bleed unit cannot be mounted.

The constructional and operational characteristics and merits of theinvention will be apparent from the ensuing detailed description, givenwith reference to the figures of the accompanying drawings, which showtwo preferred embodiments thereof by way of non-limiting example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall scheme showing the main components of the unit.

FIG. 2 is an axial section showing the discharge port of the disposablefilter of FIG. 1, said filter being of the type operating with itscartridge under pressure.

FIG. 3 is a view similar to the preceding, where the filter shown is ofthe type operating with its cartridge under vacuum.

DETAILED DESCRIPTION OF THE INVENTION

Said figures, and in particular FIG. 1, show a filter 1 of thedisposable cartridge type, known overall, comprising, starting from thetop downwards, a conduit 2 through which the fuel (such as diesel oil)to be filtered arrives, a conduit 3 through which the filtered fuelleaves, a filtering diaphragm 4, a chamber 5 for collecting the waterseparated from said fuel, and a discharge port 6 for said water.

In said port 6 there is housed a differential reading and monitoringsystem, described hereinafter, for the level 10 of the water present inthe chamber 5, below the port 6 there being a water withdrawal device 7from which there branches a conduit 8 leading to an accumulation vessel9.

The device 7 is permanently installed on the vehicle provided with thefilter 1, and is incorporated in the respective electrical system. It isconnected to the battery 11 by the cable 13 via the switch 12.

The switch 12 is controlled by the microprocessor or electronic card 14,which is connected to the ignition switch 15 of said vehicle.

In the usual manner, by means of the key 16 said ignition switch 15 canassume three positions indicated by A, B and C respectively, in thefirst A of which the vehicle engine is stationary and the respectiveelectrical system is switched off, in the second B the engine is at restand the electrical system is energized, and in the third C the enginerotates and the electrical system is live.

According to a first embodiment of the invention, in the vehiclepassenger compartment, typically on the dashboard, there is a warninglamp 17, usually present on most vehicles, typically those with a dieselengine.

Said lamp 17 is connected to a differential reading and monitoringsystem for the level 10 by the cable 170, and is controlled by the card14. Said cable 170 presents a branch 177, also connected to saiddifferential level reading and monitoring system, the purpose of saidbranch being apparent hereinafter.

Said differential level reading and monitoring system comprises, asshown in FIGS. 2 and 3, a cup-shaped member 19 the base part 20 of whichis centrally provided with a threaded through hole 33 and is sealedinside the port 6 of the filter 1.

The wall of said cup-shaped member is defined by three (or more)angularly equidistant salient fins 21 each presenting two inwardlyprojecting shoulders, namely a lower 22 and an upper 23.

The shoulders 22 and 23 define the upward travel limit of respectivefloats 24 and 25 contained within the member 19 with a certain radialslack.

Said floats 24 and 25 have a specific gravity between that of water andthat of the fuel.

The lower float 24 is shaped as a cup, in the base of which there is acentral hole coaxial with the hole 33 in the base of the member 19.

The upper float 25 is shaped in the manner of a mushroom the stem ofwhich is contained, with a certain radial slack, in the cavity of theunderlying float 24.

When the level 10 of the water present in the filter collection chamber5 is insufficient to raise the floats, as shown in FIGS. 2 and 3, thehead of said mushroom shape rests against the upper circumferential edgeof the lower float 24, and the stem of said mushroom shape is slightlyspaced from the base of said lower float 24.

This is to prevent any inconvenient sticking between the two floats,seeing that the foreign material separated from the fuel tends toaccumulate in the lowest part of the chamber 5. Respective sensors 220and 230 are positioned at said shoulders 22 and 23.

In a first embodiment said sensors 220 and 230 are magnetic proximitymicroswitches, in which case the floats 24 and 25 are suitablymagnetized, for example by means of a thin metal strip wrapped abouttheir end.

Alternatively said sensors 220 and 230 can consist of optical sensorssensitive to the colour, the same or different, of the respective floats24 and 25.

Said sensors 220 and 230 are electrically powered via a recognitionsystem arranged to identify compatibility between the disposable filter1 and that part of the bleed unit permanently associated with thevehicle, which in the illustrated example is the withdrawal device 7.

This latter comprises a casing 70 presenting at its top an externallythreaded hollow stem 71 screwed into the hole 33 in the base part 20with a gasket 44 therebetween.

Concentrically to said stem 71, on the lower face of the base part 20,there are embedded four electrically conductive annular tracks 55,external to which there is an annular gasket 66 clamped between thecasing 70 and the port 6.

The outer pair of tracks 55 is electrically connected to the sensor 220,the inner pair being connected to the sensor 230. Against said two pairsof tracks 55 there rest respective pairs of underlying electricallyconductive push rods 77 which are slidingly mounted on the upper wall ofthe casing 70 via suitable interposed elastic thrust means, not shown inthe figures, for example in the form of leaf springs.

The aforedescribed electrical connection of interface type forms saidsystem for identifying compatibility between the disposable filter 1 andthat part of the bleed unit associated with the vehicle.

Said push rods 77 are electrically connected to the card 14 positionedin the casing 70 and connected in its turn to the vehicle electricalsystem by the push-on connector 72.

To the side of the connector 72 there is a water discharge spout 73which at its bottom is connected to the conduit 8 (see FIG. 1) and atits top communicates with the stem 71 via the following interposedmeans.

In the case of a filter 1 with a vacuum cartridge (see FIG. 3), saidmeans comprise a micropump 74 interposed between said spout 73 and stem71, and driven by an electrical micromotor 75 powered by the battery 11when enabled by the card 14, said micropump, micromotor and card beinghoused in the casing 10.

In the case of a filter with a pressure cartridge (see FIG. 2), saidmeans consist of a normally closed solenoid valve.

This comprises a tube 76 sealedly clamped between said stem 71 and spout73, to form the core of a coil 78 electrically connected to the card 14.

Inside said tube 76 there are provided, from the bottom upwards, agasket 79, a valving element 80, a compressed spring 81 for maintainingthe visual indicator constantly urged elastically towards the closureposition, and a jacket 82 wrapping the upper part of the spring 81 todefine the extent of opening travel of the visual indicator 80.

The invention operates as follows.

With reference to FIG. 1, in which it can be seen that the sensors 220and 230 are connected in parallel with the lamp 17, when the level ofthe water 10 is below the predetermined value the lamp 17 remainsextinguished whatever the position of the ignition switch 15, and thefloats 24 and 25 adapt to said level. Under normal operating conditionsthe lower float 24 rises carrying with it the upper float 25.

When the water 10 exceeds said predetermined level, and the vehicleelectrical system is energized, the sensor 220 senses the presence ofthe lower float 24 and emits a signal causing the lamp 17 to light. Thelamp 17 could for example remain lit continuously, for the reason givenhereinafter.

If the vehicle engine rotates, the card 14 inhibits intervention of thewithdrawal device 7, whereas if the engine is at rest the card 14energizes the device 7 for a predetermined period sufficient for all thewater present in the chamber 5 to be discharged, with simultaneousextinguishing of the lamp 17.

If the lower float 24 is unable to rise, for example because it adheresto the soiled face of the base part 20, only the upper float 25 rises,the procedure being repeated identically when the upper sensor 230senses the presence of said upper float 25.

The electronic card 14 is preferably provided with means for selectingthe energization time of the withdrawal device 7 depending on thespecific sensor activated.

This is because activation of the sensor 230 means that there is agreater accumulation of water 10 than that associated with activation ofthe sensor 220. Consequently in the former case the period ofenergization of the device 7 is correspondingly greater. Advantageously,according to the invention the electronic card 14 is provided with meansfor indicating possible lack of energization of the withdrawal device 7when the water has reached the predetermined level, which may be dueeither to non-raising of the lower float 24 as already stated, ornon-intervention of the lower sensor 220, for example due to a fault.

Said means are typically arranged to energize the warning lamp 17 in adifferent manner depending on which sensor has emitted the overfullsignal.

For example the lamp 17 may as stated emit continuous light when thelower sensor 220 is activated, and the same lamp 17 emit intermittentlight when the upper sensor 230 is activated. Preferably the lamp 17 isenergized in the said intermittent manner starting from the secondactivation of the upper sensor 230.

By this means the vehicle driver is warned that the unit is operatingabnormally.

The merits and advantages of the invention are apparent from theaforegoing and from an examination of the accompanying figures. Theinvention is not limited to that illustrated and described, but coversall the technical equivalents of the invention and their combinations,if implemented within the context of the following claims.

What is claimed is:
 1. A unit for automatically bleeding off the waterwhich separates in a fuel filter of a vehicle, the vehicle having anengine and a switch means, said switch means operated by an ignition keyand having a first activation position in which the unit is activatedbut the engine remains switched off, the unit comprising: a disposablecontainer containing a filtering diaphragm; a separated water collectionchamber provided in a bottom thereof with a discharge port for saidwater; a withdrawal device permanently associated with the vehicle fordischarging said water when water in said collection chamber reaches apredetermined level; a sensor means permanently associated with thechamber; and a microprocessor connected to said sensor means and to saidwithdrawal device such as to activate said withdrawal device when thewater reaches said predetermined level, wherein said sensor meanscomprises a differential level reading and monitoring system sensitiveto a level between said predetermined level and a bottom of saidcollection chamber and connected to said microprocessor, saiddifferential level reading and monitoring system comprising a cup-shapedguide member, of which a base part thereof is centrally holed and sealedinside the collection chamber discharge port, and a wall thereof isperforated and positioned to enclose two coaxial floats having aspecific gravity between that of the fuel and that of water, and arespective sensor being associated with each individual float such thatsaid microprocessor energizes said withdrawal device in response to asignal emitted by either of said sensors when the ignition key is insaid first activation position.
 2. A unit as claimed in claim 1,characterized in that one of said floats faces the base of saidcup-shaped guide member and is shaped as a centrally holed bowl, and theother float is shaped as a mushroom, the stem of which is insertedstackingly into the cavity of said bowl-shaped float.
 3. A unit asclaimed in claim 2, characterized in that said cup-shaped guide memberis provided with respective stops limiting the upward travel of saidfloats, said sensors being positioned at said stops.
 4. A unit asclaimed in claim 3, characterized in that said sensors comprise magneticproximity microswitches.
 5. A unit as claimed in claim 3, characterizedin that said sensors comprise optical sensors.
 6. A unit forautomatically bleeding off the water which separates in a fuel filter ofa vehicle, the vehicle having an engine and a switch means, said switchmeans operated by an ignition key and having a first activation positionin which the unit is activated but the engine remains switched off, theunit comprising: a disposable container containing a filteringdiaphragm; a separated water collection chamber provided in a bottomthereof with a discharge port for said water; a withdrawal devicepermanently associated with the vehicle for discharging said water whenwater in said collection chamber reaches a predetermined level; a sensormeans permanently associated with the chamber; a microprocessorconnected to said sensor means and to said withdrawal device such as toactivate said withdrawal device when the water reaches saidpredetermined level, wherein said sensor means comprises a differentiallevel reading and monitoring system comprising a cup-shaped guide memberand two measurement members, each measurement member sensitive to alevel between said predetermined level and the bottom of said collectionchamber, and connected to said microprocessor such that saidmicroprocessor energizes said withdrawal device in response to a signalemitted by one or other of said measurement members when the ignitionkey is in said first activation position, said microprocessor and saidwithdrawal device being positioned in a casing to be permanentlyassociated with the vehicle and sealedly coupled removably to thedischarge port of the chamber; and a system for verifying thecompatibility between the disposable container and the withdrawal devicebeing interposed between said differential level reading and monitoringsystem and said microprocessor, wherein said compatibility verificationsystem comprises (i) two pairs of electrically conductive annular trackspositioned on an outside of a base of said cup-shaped guide member andconnected to said two measurement members, and (ii) two pairs ofelectrically conductive and elastically yieldable push rods positionedon a top of said casing and connected to said microprocessor.
 7. A unitas claimed in claim 6, characterized in that said two measurementmembers are connected in parallel with a common warning lamp.
 8. A unitas claimed in claim 7, characterized in that said microprocessor isprovided with means arranged to differently energize said warning lampdepending on which measurement member has emitted an overfull signal. 9.A unit as claimed in claim 6, characterized in that said microprocessoris provided with timer means arranged to select the period of activationof the water withdrawal device on the basis of which measurement memberhas emitted an overfull signal.